JP2001221255A - Trans-axle for four-wheel drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compactify a hydraulic multiple disk clutch part attached to a center differential gear of a vertical trans-axle in both diametral and axial directions. SOLUTION: A piston retainer is rotatably continuously provided to a clutch piston via a release bearing, a spring retainer spline-connected to a shaft part of a clutch hub is engaged to the piston retainer, and a return spring is interposed between the spring retainer and the clutch hub. By this, this device is composed so that the piston retainer is moved in the axial direction in resistance to energizing force of the return spring while rotating with the spring retainer at a constant speed with respect to the clutch hub for pressing it against a clutch part, and the hydraulic multiple disk clutch part is compactified in the diametral and axial directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertically mounted center differential device for distributing the output of a transmission to the front and rear wheels, and a hydraulic multiple disc clutch for limiting the differential between the front and rear wheels. The present invention relates to a transaxle of a four-wheel drive vehicle to be arranged.

[0002]

2. Description of the Related Art Conventionally, as a four-wheel drive power unit arranged vertically with respect to a vehicle, for example, there is a transaxle disclosed in Japanese Patent Application Laid-Open No. 2-290731 by the present applicant. In this transaxle, an engine is installed in the engine room of the vehicle, and a torque converter, a front differential device, an automatic transmission,
The center differential device and the like are sequentially arranged in series, and the drive system of the power unit can be arranged at substantially the center of the vehicle body width. .

[0003]

However, in the vertically mounted transaxle proposed by the present applicant, the overall length of the power unit tends to be long, and for a four-wheel drive, a center differential provided at the rear of the transaxle is provided. Since the device and the hydraulic multi-plate clutch are located at the toeboard and the tunnel in the vehicle compartment, if the size of the portion is increased due to an increase in the gear position, the vehicle compartment will be narrowed.

[0004] In particular, in a conventional hydraulic multi-plate clutch associated with a center differential device, a piston for operating a clutch and a pressure plate are arranged in the outer peripheral direction of a large-diameter bearing that supports a rear wheel output shaft. Since the return spring that urges the release side is also engaged with the boss of the large-diameter bearing, when trying to reduce the size in response to an increase in gears,
Although it is possible to reduce the diameter of the clutch portion, it is impossible to change the size of the bearing that supports the rear wheel output shaft from the viewpoint of load bearing, so that it is difficult to arrange the return spring. Furthermore, due to the structure of the clutch, a gear for detecting the rotation speed on the rear wheel side must be separately provided on the rear wheel output shaft, and the layout space also increases the unit overall length, making the transaxle compact. Was a hindrance to planning.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to reduce the size of a hydraulic multi-plate clutch portion associated with a center differential device of a vertical transaxle in both a radial direction and an axial direction, thereby affecting a cabin space. It is an object of the present invention to provide a transaxle for a four-wheel drive vehicle that can cope with a further increase in gears.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, an invention according to claim 1 is directed to a center differential device for distributing the output of a transmission of a vehicle to a front wheel side and a rear wheel side, and a center differential device. A hydraulic multi-plate clutch for limiting a differential between front and rear wheels by engagement of a clutch portion between a clutch drum to be connected and a clutch hub provided on a rear wheel output shaft, and accommodates the hydraulic multi-plate clutch; In a transaxle of a four-wheel drive vehicle in which a clutch piston is interposed in an extension case, the clutch axle is rotatably connected via a release bearing to the clutch piston, and the hydraulic multi-plate clutch is operated in accordance with an operating oil pressure applied to the clutch piston. A piston retainer that presses a clutch portion; A spring retainer rotatably engaged with the shaft of the clutch hub, and interposed between the periphery of the engagement portion of the spring retainer and the periphery of the shaft of the clutch hub to urge the clutch toward the release side. And a return spring.

According to a second aspect of the present invention, in the first aspect of the present invention, a gear portion for detecting a rotation speed of the rear wheel output shaft is provided on an outer periphery of the spring retainer.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the hydraulic multi-plate clutch is configured to be smaller than a maximum diameter of the center differential device.

The invention according to claim 4 is the invention according to claims 1, 2, 3
In the invention according to any one of the above, after the return spring is assembled between the clutch hub and the spring retainer, axial movement of the spring retainer by the return spring is restricted to a shaft portion of the clutch hub. And a sub-assembly in which a snap ring is engaged.

That is, according to the first aspect of the present invention, when the clutch piston of the hydraulic multi-plate clutch connected to the center differential device moves in the axial direction by the differential hydraulic pressure, the piston retainer connected to the clutch piston becomes the clutch hub. While rotating at the same speed as the clutch hub with the spring retainer splined to the clutch hub, it moves axially against the urging force of the return spring and presses the clutch part, limiting torque distribution and differential between the front and rear wheels Is done.

At this time, on the outer periphery of the spring retainer,
It is desirable to provide a gear portion for detecting the rotation speed of the rear wheel output shaft as in the invention according to claim 2, and it is possible to shorten the overall length of the unit without providing the gear portion on the rear wheel output shaft. I do. Further, it is desirable that the hydraulic multi-plate clutch be configured to have a diameter equal to or smaller than the maximum diameter of the center differential device.

Further, in assembling the transaxle, after the return spring is assembled between the clutch hub and the spring retainer, the spring retainer by the return spring is attached to the shaft portion of the clutch hub. It is desirable that the sub-assembly be locked with a snap ring for restricting the axial movement of the sub-assembly.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 relate to an embodiment of the present invention, FIG. 1 is an enlarged sectional view of a main part around a center differential device, FIG. 2 is a skeleton diagram schematically showing a transaxle of a four-wheel drive vehicle, and FIG. FIG. 4 is a front view of the retainer, and FIG. 4 is an explanatory view showing an operating state of the piston when the hydraulic multiple disc clutch is engaged.

First, a vertical transaxle of a four-wheel drive vehicle to which the present invention is applied will be described with reference to FIG. In the figure, reference numeral 10 denotes an engine, and a crankshaft 11 of the engine 10 is connected to a torque converter 13 having a lock-up clutch 12 in a torque converter case 1, and an input shaft 1 from the torque converter 13 is provided.
4 is a transmission case 3 joined to the rear of the torque converter case 1 and the differential case 2
It is input to the internal automatic transmission 30.

An output shaft (transmission output shaft) 15 from the automatic transmission 30 outputs coaxially with an input shaft 14.
The output shaft 15 is coaxially connected to a center differential device 50 in the extension case 4 joined to the rear part of the transmission case 3.

In the transmission case 3, a front drive shaft 16 is arranged in parallel with an input shaft 14 from the torque converter 13 and a transmission output shaft 15. Note that an oil pan 5 is attached to a lower portion of the transmission case 3.

The rear end of the front drive shaft 16 is connected to a center differential device 50 via a pair of reduction gears 17, 18 (transfer drive gear 17, transfer driven gear 18), and the front end of the front drive shaft 16 is connected to a differential case. 2
The driving force is transmitted to the front wheels via an internal front differential device 19.

On the other hand, the center differential device 5
0 to a rear drive shaft 20, which is configured to transmit driving force to rear wheels via a propeller shaft 21, a rear differential device 22, and the like.

In the present embodiment, the automatic transmission 30 has a front planetary gear 31 and a rear planetary gear 32,
For the front planetary gear 31 and the rear planetary gear 32, a high clutch 33, a reverse clutch 34, a brake band 35, a forward clutch 36,
An overrunning clutch 37, a low-and-reverse brake 38, and one-way clutches 39 and 40 are provided, and by selectively engaging these, a forward shift speed of four forward speeds and a reverse speed of one speed can be obtained.

An oil pump 41 is provided in front of the automatic transmission 30 so as to connect the impeller sleeve 13a of the torque converter 13 and the drive shaft 42 so as to be constantly driven. 43 are accommodated. The control valve body 43 supplies and discharges oil to and from each friction engagement element of the clutch or brake and selectively engages.

Next, the center differential device 5
0 will be described. As shown in FIG. 1, the transmission output shaft 15 and the rear drive shaft 20 are rotatably fitted coaxially via a radial bearing 23, and the transfer drive gear 17 is provided with a transmission output via a radial bearing 24 and a thrust bearing 26. It is rotatably fitted to the shaft 15.

The transfer drive gear 17 and the transmission output shaft 15 are supported by the transmission case 3 via a ball bearing 25. The rear drive shaft 20 has a cylindrical projection formed to project rearward in the extension case 4. 4a is supported on the inner circumference via a rear ball bearing 27.

A composite planetary gear type center differential device 50 is coaxially provided between the transmission output shaft 15, the rear drive shaft 20, and the transfer drive gear 17.

That is, a large-diameter first sun gear 51 is spline-coupled to the transmission output shaft 15 on the input side of the center differential device 50, and the first sun gear meshes with the small-diameter first pinion 52. A first gear train is formed. In addition, a small diameter second sun gear 53 is formed adjacent to the first sun gear 51 on the rear drive shaft 20 that outputs to the rear wheels.
The second sun gear 53 meshes with the large-diameter second pinion 54 to form a second gear train.

A first pinion 52 and a second pinion 54
Are integrally formed with a pinion member 55, and a plurality (for example, three) of pinion members 55 are rotatably supported by respective pinion shafts 58 fixed to a carrier 56, which will be described later. Are meshed with the first sun gear 51, and the second pinion 54 is meshed with the second sun gear 53.

The carrier 56 is configured such that the transfer drive gear 17 is connected to the front end to output power from the carrier 56 to the front wheels. The transmission output shaft 15 is rotatably inserted from the front, and the rear from the rear. The drive shaft 20 is rotatably inserted, and the first sun gear 51 and the second sun gear 53 are stored in the center of the space.

A hydraulic multiple disc clutch 60 for limiting the differential of the center differential device 50 is provided behind the carrier 56. The hydraulic multi-plate clutch 60 is reduced in size to the maximum diameter of the center differential device 50 or less. Specifically, a cylindrical clutch drum 61 having a rear end opened is connected to the rear of the carrier 56. The clutch drum 61 is rotatably supported on the rear drive shaft 20 via a front ball bearing 62. Further, the rear drive shaft 20
, A shaft portion 63a of the clutch hub 63 is spline-coupled, and an outer periphery of the clutch hub 63 is opposed to an inner periphery of the clutch drum 61.
4 are provided.

The clutch portion 64 includes a plurality of drive plates 65 spline-connected to the outer periphery of the clutch hub 63.
And a plurality of driven plates 66, which are spline-coupled to the inner periphery of the clutch drum 61, are alternately arranged to form a main part. When these are engaged, the rear drive shaft 20 and the carrier 56 Transmission of torque between them is possible.

On the other hand, a cup-shaped piston 67 is provided near the inner rear end of the extension case 4 so as to face the clutch portion 64, and a hydraulic chamber 68 is formed between the piston 67 and the extension case 4. Hydraulic chamber 6
A hydraulic oil supply path 69 communicates with the piston 8, and the piston 67 moves in the axial direction by operating hydraulic pressure supplied by a hydraulic control device (not shown).

The piston 67 is detented by a pin 70 so as to be movable only in the axial direction with respect to the extension case 4, and a release bearing 72 is fitted inside the cup. A piston retainer 71 having a plurality of convex portions 71a for pressing the clutch portion 64 is fitted into the inner race of the release bearing 72, and the piston 67 and the piston retainer 71 are rotatable via the release bearing 72. It will be installed continuously.

A spring retainer 73 is engaged with the piston retainer 71, and is formed around a concave portion 73a formed at the base of the spring retainer 73 and a shaft portion 63a on the rear side (piston 67 side) of the clutch hub 63. A return spring 74 for urging the clutch toward the release side is provided between the recess 63b.

The spring retainer 73 is spline-coupled to the outer periphery of the shaft portion 63a of the clutch hub 63 so that the spring retainer 73 can rotate at a constant speed with the clutch hub 63 and move in the axial direction. With the C-type snap ring 75 assembled, the return spring 7
4 restricts the movement of the spring retainer 73 toward the rear side by the urging force.

More specifically, as shown in FIG. 3, the spring retainer 73 is formed of a substantially annular member, and a plurality of return springs 74 are provided at equal intervals on the inner periphery of a central opening of a concave portion 73a. A spline 73b meshed with a spline 63c on the outer periphery of the shaft portion 63a of the hub 63 is formed, and a piston retainer 71 is formed around the concave portion 73a.
A window portion 73d from which the convex portion 71a of the piston retainer 71 protrudes is opened at a predetermined interval around a flat portion 73c with which the piston surface 71b contacts.

Further, a gear 73e is formed on the outer periphery of the spring retainer 73 to detect the rotation speed of the rear drive shaft 20 which is spline-coupled to the clutch hub 63. A rotation sensor 76 is provided opposite to the gear 73 e of the extension case 4, and a tip end of the gear 73 e is provided in order to secure the detection sensitivity of the number of rotations in accordance with the axial displacement of the spring retainer 73. Are bent to have a predetermined width in the axial direction.

That is, the projection 71a of the piston retainer 71 projects from the window 73d of the spring retainer 73 which is spline-coupled to the clutch hub 63, and the piston surface 71b of the piston retainer 71 contacts the flat surface 73c of the spring retainer 73. The contact and engagement allow the piston retainer 71 and the spring retainer 73 to move axially while rotating the piston retainer 71 and the spring retainer 73 at a constant speed with respect to the clutch hub 63. Can be detected by the rotation sensor 76.

Thus, the diameter of the hydraulic multi-plate clutch 60 can be reduced while maintaining the load resistance without reducing the diameter of the rear ball bearing 27. Since there is no need to separately provide a gear, the length in the axial direction can be reduced.

The hydraulic multi-plate clutch 60 secures the clutch capacity by increasing the number of clutches corresponding to the miniaturization.

The above-described center differential device 5
In the case 0, the assembly in which the piston 67 is assembled with the piston retainer 71 via the release bearing 72 is assembled into the extension case 4, and the return spring 74 and the spring retainer 73 are mounted on the front ball bearing 62 and the clutch hub 63, and C A rear drive shaft assembly in which the sub-assembly secured by the mold snap ring 75 and the rear ball bearing 27 are assembled to the rear drive shaft 20 is assembled to the extension case 4 and integrated, and the carrier 56 of the composite planetary gear is provided as an extension case assembly. It is configured to be assembled to a clutch drum 61 connected rearward,
The assembling workability can be improved.

In the above configuration, first, the engine 10
Is input to the automatic transmission 30 via the torque converter 13 and the input shaft 14, and the transmission power automatically shifted by the automatic transmission 30 is transmitted from the output shaft to the first sun gear 51 of the center differential device 50. Is entered.

The speed change power input to the first sun gear 51 is applied to the reduction gear 1 integrated with the carrier 55 according to the torque distribution ratio set by the specifications of each gear element.
7 and the second sun gear 53 and output.
Here, one of the wheels slips and the reduction gear 1
When a rotation difference greater than a predetermined value occurs between the seventh sun gear 53 and the second sun gear 53, the differential is limited by the hydraulic multiple disc clutch 60.

The hydraulic multi-plate clutch 60 is engaged / disengaged in accordance with the operating oil pressure supplied to the hydraulic chamber 68, and is transmitted from a hydraulic control device (not shown) via a hydraulic oil supply passage 69 to the hydraulic chamber 68.
When hydraulic pressure is supplied to the piston 6, as shown in FIG.
7 moves to the clutch part 64 side, and presses the clutch part 64 by the piston retainer 71 connected to the piston 67.

At this time, the piston retainer 71 is rotating at a constant speed with respect to the clutch hub 63 together with the spring retainer 73 spline-coupled to the clutch hub 63, but the rotational force of the piston retainer 71 is equal to that of the piston retainer 71 and the piston 67. And the piston 67 moves in the axial direction without rotating.

That is, the piston 67 is prevented from rotating with respect to the extension case 4 by the pin 70, and only the inner race rotates without rotating the outer race of the release bearing 72.
7, the piston retainer 71 moves in the axial direction while rotating.

As a result, the piston surface 71b of the piston retainer 71 presses the flat portion 73c of the spring retainer 73 to move the spring retainer 73 in the axial direction against the urging force of the return spring 74. A plurality of drive plates 65 spline-coupled to the outer periphery of the clutch hub 63 and a plurality of drive plates 65 spline-coupled to the inner periphery of the clutch drum 61 by the protrusion 71 a of the piston retainer 71 protruding from the portion 73 d pressing the clutch portion 64. Multiple driven plates 66
And the torque distribution and the differential rotation to the front drive shaft 16 via the reduction gears 17 and 18 and the rear drive shaft 20 via the second sun gear 53 are restricted.

In this case, since the hydraulic multi-plate clutch 60 is more compact in both the radial and axial directions than in the conventional case, it is possible to cope with a further increase in the number of gears without affecting the cabin space. be able to.

[0046]

As described above, according to the present invention, the hydraulic multi-plate clutch portion attached to the center differential device of the vertical transaxle can be made compact both in the radial direction and the axial direction, so that it can be installed in the vehicle compartment space. Excellent effects can be obtained such that it is possible to cope with a further increase in the number of gears without affecting.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part around a center differential device.

FIG. 2 is a skeleton diagram showing an outline of a transaxle of a four-wheel drive vehicle.

FIG. 3 is a front view of a retainer.

FIG. 4 is an explanatory diagram showing an operation state of a piston when a hydraulic multi-plate clutch is engaged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 4 ... Extension case 20 ... Rear drive shaft 50 ... Center differential device 60 ... Hydraulic multi-plate clutch 61 ... Clutch drum 63 ... Clutch hub 64 ... Clutch part 67 ... Piston 71 ... Piston retainer 72 ... Release bearing 73 ... Spring retainer 74 ... Return spring

Claims (4)

[Claims] 1. A center differential device for drivingly distributing a transmission output of a vehicle to a front wheel side and a rear wheel side, and a clutch drum connected to the center differential device and a clutch hub provided on a rear wheel output shaft. A hydraulic multi-plate clutch for limiting the differential between the front and rear wheels by engagement of the clutch portion, and a clutch piston interposed in an extension case accommodating the hydraulic multi-plate clutch.
In a transaxle of a wheel drive vehicle, a piston retainer rotatably connected to the clutch piston via a release bearing and pressing a clutch portion of the hydraulic multi-plate clutch according to an operating oil pressure applied to the clutch piston; A spring retainer engaged with the piston retainer and rotatably and integrally engaged with the shaft portion of the clutch hub; and a spring retainer interposed between the periphery of the engagement portion of the spring retainer and the periphery of the shaft portion of the clutch hub. A transaxle for a four-wheel drive vehicle, comprising: a return spring for urging the clutch portion toward a release side. 2. A transaxle for a four-wheel drive vehicle according to claim 1, wherein a gear portion for detecting a rotation speed of said rear wheel output shaft is provided on an outer periphery of said spring retainer. 3. The transaxle for a four-wheel drive vehicle according to claim 1, wherein the hydraulic multi-plate clutch is configured to be smaller than a maximum diameter of the center differential device. 4. After assembling the return spring between the clutch hub and the spring retainer,
4. The clutch hub according to claim 1, further comprising a sub-assembly in which a snap ring for restraining an axial movement of the spring retainer by the return spring is locked on a shaft portion of the clutch hub. 4 described in one
Transaxle for wheel drive vehicles.